Yes, you do – for a couple of reasons. The first is that hydration pressure from the evaporation of water during the concrete curing process can still be a problem, depending on curing conditions, amount of excess water used in the concrete mix, and cure time of the slab. Best to measure this rate of moisture evaporation with a plastic sheet test to determine the time it takes for moisture to form on the underside. If this time is shorter than the tack free time for our primer (about 6 hours for Primer LVFC at 70°F), then you must wait before applying the material.
While the presence of the vapor barrier should prevent any subsurface moisture pressure from adversely affecting the coating, it is still a good idea to run calcium chloride tests to provide an extra measure of insurance, as problems can result from the barrier being penetrated during the installation of the concrete. This is especially a problem if a thin (6 mils) film is used. We recommend a minimum 10 mil or greater, reinforced vapor barrier be used to guard against this ripping of the film during installation. The other reason for running calcium chloride tests is in cases where the barrier is placed below sand and gravel, rather than directly under the slab, as entrapped moisture in the sand could result in a high enough water content to cause delamination of the coating. Note that for our ¼” trowelled systems, we recommend a maximum allowable water content of 10 pounds, and 5 pounds or less for “thin film” applications.
Our contractors faced with short customer down times, often ask us how to best apply our decorative quartz floors within very narrow window, sometimes as little as 36 hours. Typically, a color quartz floor entails two broadcast coats with an additional single clear coat to seal the system. With our regular PM DBS system, using our resin and our ICO Sealer top coat, intervals between coats are typically 12-24 hours depending on temperatures.
Of course, the contractor could apply the color quartz as a one-step trowelled system, but this method is dependent on installer skill and experience and may not look as good as a double broadcast floor and it still requires a clear seal coat. A better choice would be to use our Floor Coating FC clear coating or PM fast cure resins for all three steps. Jobs that have been installed with this system at ambient conditions have been completed in as little as 36 hours, from shutdown to start up. These materials broadcasted to refusal with color quartz can be ready for the second coat within about six hours. The same material can also be used as the final sealer coat, as it has excellent clarity and also cures fast enough to return the floor back in service 12 hours after the last application. It’s a tight squeeze but can (and has) been done in several retail establishments, notorious for short windows. In cases where UV resistance is key use ICO Ure Guard 80 or PM 500 urethane.
The slight extra material cost (about $.25/SF for the 1/8” double broadcast system) is well worth it when it means you can accommodate a good customer’s wishes. The other advantage of stocking this Floor Coating FC clear material is that, in conjunction with one of our tint concentrates, it can be easily converted to a pigmented coating as needed. All you need to do is stock quart containers of our ICO Tint (each quart is sufficient for a 4 gallons of the clear coat).
We often hear from contractors that they apply Milamar products indoors, but many have never used our products for outdoors. There are some precautions to take when moving into the outside world:
Outdoor applications of epoxies entail a little more planning to ensure a quality installation. First, it is important to plan your installation so that it is done at a time of steady or falling temperatures; otherwise, out gassing caused by expanding air in the concrete can result in bubbles and pinholes in your finished coating. Note that it is always recommended to fill bug holes and other voids in concrete berms prior to applying the coating, as this greatly reduces the chance of pin holing. This can be accomplished with ICO Gel.
Another precaution is that you should not lay any of our 100% solids materials in direct sunlight, as this can result in large blisters being formed, especially on as-trowelled floors (this is less of a problem when applying a slip resistant coating/broadcast system). In areas subjected to freeze/thaw cycling, we suggest providing an especially aggressive profile (>40 grit size) when preparing the concrete to better lock in the epoxy with a good mechanical bond. And since most of this work is on slabs-on-grade, testing moisture content by conducting a calcium chloride test before applying your coating is mandatory, as is using a very good moisture-tolerant epoxy primer that is chemically resistant to the high pH’s of concrete. In this case, we recommend ICO Primer LV
We are also questioned about epoxy degradation under UV exposure. We have many outdoor installations of our coatings that are almost 30 years old and except for severe color fade and loss of gloss, the coatings are still intact. However, if appearance is an issue with your customer than you can always add our Ure Guard 80 or PM 500/550 as a UV-protective coating, albeit at a sacrifice in some chemical resistance, especially under concentrated acids.
Part of the job of resurfacing an old floor typically involves treatment of cracks. Our recommended procedure is that structural cracks at least 1/8” wide should be routed out ½” or so in width and about 1” deep in a v-notch pattern. After cleaning thoroughly with muriatic acid and neutralizing it, the next step is normally to use a crack filler material like our ICO Gel, allow it to dry at least tack free, then apply the final overlayment.
To save time, use of our resin-rich material enables you to fill the crack and apply the finished floor simultaneously. The trowelled mix is “wet” enough to allow for excellent adhesion, but is thick enough so as not to seep out of the crack. It helps to do this on floors that are broadcast with grit for texture as this helps hide any imperfections that might appear due to the difference in depths. This technique can also be used in filling in key ways at entrances and around drains at the same time you are applying the floor. Thus, you have saved a step and valuable time by not having to wait for the crack filler material to dry hard enough so that your finished floor can be applied.
Another useful tip is in the application of our decorative quartz floors. Our standard system, PM DBS, consists of two broadcast coats of our base coat clear resin, saturated with a blend of medium-sized color quartz to provide the desired color, then sanded and top coated with a clear coat of our ICO Sealer epoxy clear coat at about 15-16 mils. This system yields a one eighth inch thick finished floor with a moderate-rough texture, depending on how much sanding is done between coats. In facilities that desire low-maintenance but high gloss floors, it is recommended to apply a second clear coat at about 5 mils, but this time using our urethane, ICO Ure Guard 80 or 500. This step achieves a smoother, easier-to-clean finish with much better gloss retention and UV protection, thereby eliminating the need for waxing.
Customers frequently ask what our recommendation is for the minimum film thickness for a coating applied over concrete.
We see wide ranging specifications from 2-3 mils DFT (dry film thickness) on up. While the exact thickness will depend on a number of factors, including condition of the existing floor, desired life expectancy, type of traffic, budget, chemical exposure and finished appearance, there are a few essential facts that must be considered in trying to arrive at a minimum thickness.
Any floor coating manufacturer will specify that the floor must be clean and abraded, as a good mechanical “profile” is essential to long-term adhesion. In today’s environment, it is almost unheard of any more, at least on commercial-sized applications, to acid or chemically etch a floor; hence, mechanical prep is by far the most prevalent form of surface prep. Mechanical shot blasting is the most widely used form of prep and while the finished profile can widely vary, most material manufacturers want a minimum profile of 80 grit, with 60 grit more common for “thin film” coatings. Such a grit size corresponds to a profile range of 3.5-10mils. For more contaminated surfaces, or where cure and seal compounds must be removed, it is not uncommon for a 40 grit texture, equivalent to up to 16 mil maximum profile to be obtained.
With such profiles, any coating thickness not designed to cover the peaks of the profile is not doing its job, and, in fact, is leaving pinholes in the finished surface. For this reason, we recommend a two-coat, 20mil minimum thickness. Greater thicknesses are recommended on rougher floors, with a 60 mil self-leveling floor coating considered best for badly pitted floors. Anything less than 20 mils is going to be ineffective long term, especially in situations where the coating is expected to provide a protective barrier against chemicals, fuel oils and other contaminants. The advent of 100% solids epoxies and urethanes make achieving these minimum thicknesses in two coats much easier than in the case of solvent-based paints.